Method of producing trichloropropionic acid



Patented May 14, 1946 7 Memory oF-rnonUcmG 'rmonLoaoraorromc ACID Joy G. Lichty, Stow, Ohio, asslgnor to Wingfoot Corporation, Akron, Ohio, a corporation of Delaware Serial No. 440,928

No Drawing. Application April 29, 1942,

2 Claims. (CL 280 539) This invention relates to the preparation of trihalopropionic acid and trihalopropionamide :by hydrolysis of trihalopropionitrlle. The hy-' drolysis is carried out in an acid solution. The invention will be described more particularly as applied to the chloro compounds although the bromo and iodo compounds may be prepared in the same way.

The followingexamples are illustrative of the process and although sulfuric acid has been employed in the example, other acid media. may be used.

. Alpha dichloro'beta chloro propionic acid A reaction vessel is equipped with a stirring device and a reflux condenser. 'Twenty mols of concentrated sulfuric acid are introduced into. thereaction vessel. Fortymols of water are added rapidly, the acid being stirred meanwhile. The

any temperature above 120 (1., may be used but at this temperature the acid should be heated for a longer time. Furthermore, the concentration of the acid may be varied and other mineral acids, such as hydrochloric, phosphoric, etc. may be used. Under the conditions of the above example, a ratio of one part of nitrile to ten parts of water to 2 parts of sulfuric acid gave only a small yield of trichloro propionic acid when heated at 120-125 for six hours. For most satisfactory results a concentration of at least 50% of sulfuric acid should be employed.

low.

It is also possible to hydrolyze trichloropropionitrlle to trichloropropionamide as set forth be- Alphadichloro beta chlor propiondmtde Twenty four parts by weight of dry hydrochloric acid gas was. passed into a solution of 95.3

diluted acid is then brought to a'temperature of parts of trichloropropionitrile in 67 parts of an- 140-155" C. and ten mo]; of trichloro propionitrile are added gradually at such a rate that the temperature is maintained at a temperature above 140 C., e. g. a temperature between 145-150 C. by the heat of the exothermic reaction. If the temperature is maintained between 145-150 C. the addition of nitrile should consume about one and a half to two hours. When the whole of the 'nitrilehas been added, the mixture is maintained at an elevated temperature to complete the reaction, e. g. at 140-150 C. for about four hours longer.

Then the mass is allowed to cool down to cause separation of the crude trichloro propionic' acid from the aqueous solution of ammonium bi'sulfate. It may, for example, be cooled to about 80 C. The aqueoussolution is heavier than the acid. At temperatures below about '75 C. the entire mass tends to crystallize and this, of course, is to be avoided.

The crude acid which is thus separated is dis-.

tilled until the boiling point rises to about 120 C./60 mm. The residue consists of practically pure alpha dichloro beta chloro propionic acid and for some purposes may be used as such. The acid may, if preferred, be further purified by distillation. It has a boiling point of approximately 140 C./40 mm. The yield as undistilled chloro propionic acid is practically quantitative. The yield of the distilled product is about 93%.

The preferred temperature referred to in the example gives rapid and substantiallycomplete conversion. A lower temperature, for example hydrous isobutyl alcohol. The solution became viscous. After a period of time water was added to the product. The lower layer was removed and the more volatile ingredients were distilled oil from it. A residue of 100.2 parts remained which rystallizing in my application Serial No. 412,471, filed September 28. 1941.

I claim: we 1. The one-step-method or producing trichloropropionic acid which comprises gradually adding about one molecular part of trichloropropionitrlle to a sulfuric acid bath formed by diluting about" two molecular parts of concentrated sulfuric acid with about four molecular parts of water while stirring and maintaining the temperature of the bath at about 140-150 C. throughout the reaction until the nitrile is substantially completely converted to the acid.

I 2. A- method of producing trlchloropropion'ic acid which comprises hydrolyzing trichloropropionitrile in a sulfuric acid bath formed by diluting about 2 parts ofconc'entrated sulfuricacid with about 4 parts of water at a temperature above about 0; until the nitrile is substantially completely converted to the acid.

' JOY sum. 

